The invention relates to the powder paint spray coating of substrates using modular applicators mountable into a programmable, robotically maneuvered housing.
Electrostatic spray applicators are widely used in the coating industry for powder spray coating of substrates such as automotive vehicles. Spray gun applicators mounted on programmable robots used in automated production lines are advantageous in applying uniform coatings of powder to irregularly shaped substrates. Alternatively, rotary electrostatic spray applicators, known as bell cup applicators, may be used for applying powder paint coatings to larger areas of substrates. Such bell cup powder applicators are affixed to turbine housings through which is fed the powder to be sprayed in the form of an air-powder mixture under pressure. Various bell cup applicators are known and are disclosed and described, for example, in my commonly assigned, co-pending U.S. patent application Ser. No. 09/993,011, incorporated herein by reference.
In such applications, the coating material is generally applied as a fine powder spray which is, after coating, subsequently baked in a vehicle paint oven to form a durable, finished coating thereon. As a substrate to be coated passes the applicator assembly, electrically charged powder particles are discharged in a dust form. The ionized powder particles are attracted to the electrically charged (grounded) substrate, thereby providing an evenly distributed coating on the substrate.
Spray gun applicators, which are generally used to spray coat a more narrowly defined and irregular surface, are normally affixed through a wrist component to the end of a robot arm, and dual spray-head guns for such applications are known. See, for example, U.S. Pat. No. 5,320,283.
Also known are apparatus and a method for liquid paint spraying, as compared and contrasted with powder coating, wherein two paint spray guns are mounted on a common manifold block. Shaping air, atomizing air and paint are fed to the guns. Each gun is individually controlled by a respective solenoid valve and, during operation, a selected one of the spray guns is robotically positioned adjacent a surface to be painted and then operated to apply paint. See, for example, U.S. Pat. No. 4,692,358.
The powder coating apparatus of the present invention, in contrast to the known prior art, provides a plurality of modular, robotically maneuvered, differing powder applicators, all removably mounted in a common housing and connected to a common powder supply. On demand, the coating operation can be switched nearly instantaneously from the use of a spray gun applicator to the use of a rotary bell cup applicator, and vice versa.
Electrostatic spray apparatus for applying powder coatings to substrates is provided. The apparatus includes a universal main wrist receptacle means removably affixed to the end of a multi-axial, three dimensionally maneuverable arm. The receptacle means has attached thereto a modular rotary bell cup powder spray applicator. The receptacle means has, in addition, connection means to which a modular powder spray gun applicator may be optionally and removably affixed. The apparatus includes means for spatially switching from one applicator to the other applicator such that a selected one of the applicators may be positioned adjacent a substrate for coating, on command. The apparatus includes control means for selectively controlling the supply of spray powder to a selected one of the applicators, on command. A supply of powder is maintained in flow communication with whichever applicator is operational.
The receptacle preferably has both a modular rotary bell cup applicator and a modular spray gun applicator, each removably affixed thereto.
The optional spray gun applicator may be omitted and in its connection a removable plug may be inserted. The switching command may be effected electrically or pneumatically.
Control valves are provided which control the flow of powder supplied to the bell cup applicator and to the spray gun applicator, on command. The control valves may be controlled electrically or pneumatically. Preferably, the control valves are pneumatically sealable pinch valves.